Place the chicken in a bowl with the oil, fish sauce, onion, garlic and pepper and toss to combine. Heat a large frying pan over medium high heat. Add the chicken pieces and brown. Add the soy sauce. Cover the pan, reduce the heat to low and cook for 15 minutes, stirring occasionally.
Increase the heat to med-high, add the palm sugar, water and lime juice. Cook uncovered for 3 to 4 minutes, or until the sauce is rich and syrupy and chicken is cooked through.